Directional gyro



1111.9, 1945. 1 FQ CARTR Em 1 2,366,707

DIRECTIONAL QYRo Filed April 5o, 1941 2 'sheets-sheet 1 INVENT'ORS LESLIE F. CARTER FREDERICK D. BRADDON THl-:m ATTQRNEY L. F. CARTER ETAL Jan. 9, 1945.

DIRECTIUNAL GYRO Filed April 30, 1941 2 Sheets-Sheet 2 y INVENTORS LIE .'F. CARTER FRE RICK D. BRADDON- 53 www THEIR ATToNEv y Patented Jan. 9, 19.45

l acceso:y DntEcTIoNAL Gmo Leslie F. carter, Leona, N. J., and Frederick D. .Braddon, Babylon, N. Y., assignors to Sperry Gyroscope Company, Inc corporation of New York Brooklyn, Y., 'a

l Application April 30,1941, serialN. 391,060v s claims; (01.-74-5).

This invention relates .to gyroscopes and particularly to Jan improvement in pneumatically operated gyros of the direction indicating type andthe gimbal system therefor.

One of the objects; of the invention. is to avoid any drift of the gyro resulting from disturbing forces imposed on the gimbal orV ring systeml through the effect of air turbulence within the housing.

Another object is to obviate precessional forces arising frorn air leakage at the gimbal bearing air seals Vin the conventional type of directional gyro in which theentire housing for the parts is evacuated.

An important feature of the invention consists in constructing the gimbal vor vertical ring sys-l .tem of thegyro with passageways so that the interior of the enclosed rotor bearing case of the,v instrument supported thereby may be directly evacuatedfrom the exterior of the outer housing withoutr evacuating the housing itself asl is ycommon in the art. Because of this feature, the de- A sirable advantage is obtained'of being ablegto run, calibrate and .balance the instrument with the housing open to give access to the gyroscope, V which cannot be done with the evacuated type of housing.

According to our invention, we retain the outer casing or housing to provide instrument but provide it with a separable cover plate which may be removed without disturbing the instrument and which is preferably put in place after the required calibration and balance tests on the instrument have been completed, the

Vinstrument then performing in the same manner as'it did when not completely housed which is Yvirtually impossible with the usual evacuated casev type ofinstrument.

Another feature of the invention resides inthe provision of a special air sealed chamber at one of the muntings of the vertical gimbalring of the instrument which facilitates the withdrawal of air from an enclosed rotor bearing case having jet producing openings in the body thereof.

A further importantfeature ofthe invention' consists in 'the utilization of separate passage- I ways in the vertical ring structure of th lgyro having discharge ports by which an erecting torque may be exerted `about'the vertical axis of the ring, each of the passageways bein'g provided vwith oppositely functioning air valves so that a differential discharge of air fromv the ports is obrotor of the gyro `from a perpendicular relation to the verticalaxis of the ring.

Other objects, features and structural details of the invention will be apparent from the following description when read in connection with the accompanying drawings, wherein Fig. 1 is a front elevation of the improved gyroscopic instrument showing the way it appears to the observer. f

Fig. 2 is a side vertical section of the preferred form of directional gyro instrument illustrated in f the drawings. d

Fig. 3 is a section showing in`detail the particular sleeve construction employed in Fig. 22 in pro- .15y viding the discharge ports for the air by means of which the rotor case of the gyro is maintained erect.

Figs.4 and 5 are enlarged detail cross-sections showing corresponding pOsition views of theright and left hand air valves utilized in the form of the invention shown in Fig. 2.

Figs. 6 and 7 are views similar to Figs. 4 and 5 illustrating the. manner in which the opposingly situated valves operate when the rotor bearing 25` case is tilted =so that thel spin axisof the rotor lferent compa' card construction in theim protection for the thereof is not in perpendicular relation to the axis of the ring.

" Fig. 8 is a view similar to Fig. 1 showing a difproved instrument, arid Fig. 9 is a view similar to Fig. 2, showing a mod-v iiled instrument, constructed in accordance with the present invention, enclosed in'an air-tight outer' casing in which a superatmorspheric pressure is maintained to spin the rotor of the gyroscope and maintain the rotor case level.

`With particular reference to Figs. 1 and 2, in

the preferable form in which 'the present inventive concepts aredisclosed, the improved gyro of the direction indicating type is shown as enclosed within an outer .casing or housing I, one side or end of which is constructed as aremovable cover 2 which contains an air filter 3 and a pipe connection 4 leading to a suitable suction. means which draws the air from the instrument in the direction indicated by theA arrow. The casing I tained which exerts a torque proportional in amount to the degree of tilt of the spin axis of the also includes a front windowV 5 through which a suitablyl graduated compass card 6 is visible to the observer of the instrument. A mask 8 Von which lub-ber lines I0 and I I are marked is located in front of thecard 6,1m this instance.

Card 6 is mounted for rotational movement 4with shaft I2 which is jqurnalled in bearing' I 3 and driven by large gear Il which meshes with gear I5 situated on the lower portion of the vertir cal gimbal ring I6. A desirable pivotal mounting is provided for the vertical ring I6 which in the /construction shown is accomplished by means of trunnions I'I and I8, and the respective ball bearings 20 and 2 I. In the improved instrument, the enclosed rotor bearing case 221s rotatably mounted on the horizontal trunnions 23 and 24 in ball bearings 25 and 26, respectively, located on and forming part of the vertical gimbal ring I 6. An air spun rotor element of any desirable type is contained within the rotor bearingcase 22, one of the blades of the rotor element, on which the air ,impinges t drive the rotor, being indicated at `2'I. In this instance, air is directly drawn into the enclosed rotor bearing case 22 through thefprovided jet producing openings 28 and 29 therein, the air at atmospheric pressure being admitted to the interior of the housing I by way of lter 3.v Such jet producing openings form a means by which air is supplied to the enclosed aseavov passageways 30 and 3| provided in a portion oi l provide the herein disclosed air valves. The position of the left-hand air valve, as viewed in Fig. 2, is shown in Fig. 4 while that of the right-hand valve is shown in Fig. 5, both valves being indicated therein as half open which permits an Pequal flow of air through each of the same. Such a position may be considered the normal position of the respective valves, the same being assumed when the horizontal spin axis of the gyro rotor is perpendicularly disposed with relation to the axis of the vertical ring or ,in other words when the gyro case is properlylevel. respective trunnion passageways 30 Vand 3l and air valves divide the air traveling Vfrom the interior of the rotor bearing case 22 and in connection with the laterally directed ports 34 and 35 in a sleeve 36 fixed onthe base trunnion I8 of the vertical ring I6 provides the' levelling means 4 for the improved gyro. Pipe members 31 and 38, respectively, are employed in this instance to suitably connect the passageway 32 with port 34 and passageway 33' with port 35. The opposing ports 34 and 35 inthe sleeve 36 are situated the same radial distance from the center of the axis of rotation of the ring I5 to obtain the specified normal torque' balance of the levelling means when the rotor case is level. The airexhausting from the ports 34 and 35, when the valves are positioned as shown in Figs. 4 and 5, exerts equal and opposite torques on the ring I6 about its vertical axis to provide this balance.

The function of the respective air valves in the horizontalgimbal bearings which support the enclosed rotor case is to differentially vary the airow from the ports 34 'and 35 in the provided sleeve 36 in proportion to the degree of tilt of the axis of the rotor of the gyro from a normal position. Relative positions of the two valves are shown in an extreme instance, in Figs. 6 and 7, in which the passageway 32 is fully opened while passageway 33 is entirely closed. In such an event, the air is only exhausted throughl port 34 The` to produce a torque about the axis of the vertical ringl I6 in the proper direction to effect a pre` cessional movement of the rotor case to a levelled condition. The created differential levelling torque about the vertical axis of ring I6 is consequently made proportional in amount to the degree of tilt of the rotor bearing case from its levelled position in accordance with the teaching of the present invention. Also, the direction that the torque is effective in depends on the direction in which the gyro, case tilts on its horizontal axis.

The air from ports 34 and 315 discharges into an air sealed chamber or enclosure 9 formed in the present instance by an interiorly extending cylindrical member {9} connected to the base of housing I, and a longitudinally movable cylindrical element 39 which is a part of thecaging mechanism employed in the present instrument. Passageways 40 and 4I are situated in the member I9, the same connecting the chamber 9 with the passageway 42 in the base of the housing I. The passageway 42 is aligned with the opening in the cover 2 in which the pipe connection 4 to the suction source is located, such system of passageways enabling the suction source to continually evacuate the chamber 9 and provide a means by which the air is withdrawn from the chamber.

From the foregoing it will be obvious that the cover 2 may be removed entirely from the rear of the casing l to give ready access to the gyroscope, and at the same time the gyro may be operated and tested in the same manner as if the casing I were closed by the back cover 2. ThisY was not possible in the majority of vacuum driven aircraft instruments in use, since the usual practice is to exhaust air from the interior of the casing I, which of course is impossible if the back cover is removed. In our invention on the other hand, the gyroscope may be fully operated without the back cover merely by connecting the exhaust pump to passage 42.

In the modiiication of the invention shown' in Fig. 9, an outer air-tight casing 50 is provided for the instrument, the same being suitably supplied with air at a pressure above atmospheric by means of a pump through the pipe connection 5I. In this instance, the bearing 52 provided in the base of the casing 50 is air-tight and the trunnion 53 for the ring I6 extends exteriorly of the provided casing. The ports 34 and 35, in

this form of the invention, connect with the pasthrough the jet producing openings 28 and 29m the enclosed rotor case to spin the -rotor element, the same then passing through the air valves arid passageways previously described to exhaust to the atmosphere exteriorly of the casing and maintain the rotor bearing case level in accordance with the teaching o f the present invention.

With particular reference to Figs. 1 and 8, two different arrangements of the compass card and mask are shown. In Fig.y 1, the card 6 is provided with an outer andinner set of concentrically spaced graduations thereon, each of which divides the respective circles into suitable parts of the total of the indicated 360 thereof. In this instance, the noted-indications on the inner circle aseavo'r the same indications contained on the outer circle. The upper part 'of' the mask 8 is constructed to include an upwardly extending semi-circular portion 4.3 which covers the indications and graduations of the inner circle while permitting the ob- .server'to read the outer circle graduations and the indications thereof with reference to the lubbers line IIL- As shown in Fig. 1. this indication i A small opening 44 having ones'ide arcuate in form is provided in the lower portion of the mask 8. The arcuately `formed side of the` opening Ilis located in the mask so Vthat the indications and graduations on the inner circle of the card 6 are comparable withv the lubbers linel l I while the -outer circle is completely covered.v As noted herein, the indication on the inner circle graduation,.with reference to the line Il, is 180. The

proportional to the degree of tilt of said case with respect to the vertical axis of said ring is obtained, and whereby the gyroscope may be run and tested by withdrawing air from said chamber-without the other part of said housing.

3. A pneumatically operated directional gyro having `a rotor, an enclosed rotor bearing case, meansvby which thesupplied air spins the rotor, a rotatably mounted vertical ring within which the case is mounted on trunnlons to pivot about l a horizontal axis, an air sealed chamber at one of the mountings of the vertical ring, said vertical ring and the trunnlons for the case having two separate passageways therein by which air flows from theinterior ofthe rotor bearing case to exhaust into-theL chamber, valve means controlled by thertrunnions to regulate the amount observervis consequently aware of the required position, at all times, into which to bring the card 6 to obtain an accurate and complete change in the heading of the craft on which the improved instrument is employed.

With reference to Fig. 8, a change of the arrangement of card 6 and mask 8, as illustrated in Fig. 1,' is-shown.v In this ligure, the indications are placed on opposite' sides of a single graduated circular scale I5 and the shape of the mask 8 is l altered slightly to accommodate l'this change.

While we have described what we consider 'to be highly desirable embodiments of your invention, itis obvious that many changes in form could be made without departing from the spirit of our invention, and we, therefore, do not limit ourselves to the exact form herein shown and de-A scribed, nor to anything less than the whole of our invention as herei'nbefore set forth, and as` hereinafter claimed.

What is" claimedis: Y

1. A pneumatically operated directional gyro having a rotor, an enclosed rotor bearing case, an aperture therethrough by Which'the supplied air spins the rotor, a rotatably mounted vertical ring within which the case ls mounted to pivot about a horizontal axis, Said ring and rotor bearing case mounting being provided withn a pair of passageways, each pair-comprising a plurality of of air flowing in the respective passageways lin the vertical ring, means for exhausting the air from the passageways into the chamberto obtain a levelling torque about the vertical axis of the ring proportional in 4amount to the degree of tilt of the rotor bearing case from a level position.i

and means by which the air is withdrawn from the chamber.

4. A pneumatically operated directional gyro having a rotor, an enclosed rotor bearing case,

means by which the supplied air spins the rotor,

a ring mounted for freedom vabout a vertical axis and upon which the case is mountedon trunnions to pivot about a horizontal axis, an air sealed chamber at one of the mountings of the vertical a diierential levelling torqueV proportional in amount and reversible in direction with the deconnecting channels extending from the interior of the case andterminating in laterally directed ports in said ring from which the exhaust air is adapted to normally exert equal and opposite tor-ques on said ring about its vertical axis and la valve between the channels in each passageway 'operative to oppositely vary thel air flow in the respective passageways upon relative tilt of said case and Yvertical ring to obtain a diierential ilow of air from the ports thereby producing a levelling torque lfor the rotor bearing case.

2. In va pneumatically operated directional l gyroscope, a separable, two part housing, a rotor,

a rotor bearing case having an air jet intake for spinning the rotor, and a vertical ring rotatably mounted within one 'part of said housing about a vertical axis, of pivoted means mounting said case in said ring for movement about a horizontal axis, said vertical ring and pivoted means having two lseparate passageways therein by whichair flows from the interior of the case through the vertical ring, ports in said ring positioned to exert opposing torques about the vertical axis of said ring', a chamber within said part of said housing lenclosing said ports. and airvalves disposed in each of said passageways controlled by the relative tilt of said case and ring, whereby a dinerential levelling torque about the vertical axis gree and direction of tilt of the spin axis of the rotor from a perpendicular relation to the vertical axis of thev ring, and means by which the air is withdrawn from the chamber.

5. A pneumatically levelled directional gyro having a housing, a rotor. an enclosed rotor bearing case, a vertical ring, trunnion supports' be: tween said case and ring having channels therein to the interior of said case, jet means through the case for spinning the rotor, the portions of the trunnlons adjacent the vertical ring being constructed to form oppositely positioned air valves in coniunction with passageways situated in the respective sides 'of the vertical ring to-difierentially vary the airnowV therethrough upon tilt of` said case, vertical trunnion supports between said ring and said housing, at least one of which ex- .tends beyond .said housing and through which said passagewaysextendto terminate in laterally directed ports beyond the housing from which the exhaust air normally exerts equal and opposite torques on said ring about its vertical axis, and means for maintaing said housing under pressure, whereby compressedair is forced through said J'et means to spin the rotor and the exhaust air diil'erentially 'the housing'at flows through said ports withoutv variable ratesl controlled .by the tiltof the casing in the vertical ring.

6. A pneumatically operated directional gyro having a rotor, an enclosed rotor bearing case, an aperture therethrough by which the supplied air spins the rotor, a rotatably mounted vertical' ring within which the case is mounted to pivot about a horizontal axis, said ring and rotor bearconnected passageways, each pair extending from the interior of the case and terminating in laterally directed ports in said ring from which the exhaust air is adapted to normally `exert equal and opposite torques on said ring about its vering case mounting being provided with a pair of tical axis, said ports being Within a small chami berfmeans whereby air maybe exhausted from said chamber, andv a valve in each passageway operative to oppositely vary the air ow in the respective passageways upon relative tilt of said case and vertical ring to obtain a diierential flow of air from the ports thereby producing a levelling torque for the rotor bearing case.

7. In an air spun directional gyroscope, a rotor, a bearing casing enclosing the same and having a jet-forming aperture therein for spinning the rotor, a vertical ring, horizontal bear ings supporting said casing in said ring for movement about a horizontal axis,`a closed outer housing, vertical bearings supporting said ring for turning about a vertical axis ln said housing, an

exhaust passage leading from within said casing through at least one of said horizontal bearings, through said vertical ring and through at least one of said vertical bearings, and terminating in a port located without the space enclosed by said housing and surrounding said gyroscope, and

means for maintaining the interior ot said kousing under super-atmospheric pressure, wherebyl compressed air is forced through said jet aper-l ture to spin the rotor and the disturbing effect of eddy currents from the exhaust air from the gyroscope is avoided.

8. A pneumatically levelled directional gyro having a housing, a rotor, an enclosed rotor bearing case, a vertical ring, trunnion supports between said case and ring having channels therein to the interior of said case, jet means through the case-for spinning the rotor, theA portions of the trunnions adjacent the vertical ring being constructed to form oppositely positioned airy 4 valves in conjunction with passageways situated in the respective sides of the vert cal ring to difierentially vary the air iiow therethrough upon tilt of said case, vertical trunnion supports between said ring and said housing, at least one of which extends beyond said housing and through which said passageways extend to terminate in laterally directed ports beyond the space around the gyro enclosed by the housing from which the exhaust air normally exerts equal and opposite torques on said ring about its vertical axis, and means for maintaining a difference in pressure between the space in said housing and said exhaust ports, whereby air is forced through said jet means tospin the rotor, the exhaust air differentially ilows through said ports to eliminate tilt of said case, and eddy curr'nts within the housing are prevented.

" LEsuE E. CARTER..

REDERICK D. BRADDON. 

